Bacteria and Disenctants

Purpose:
How concentration can affect the performance rate of disinfectant in killing micro-organisms.

Equipment:
3 agar plates, Marker pen (permanent), Ruler, cello-tape, filter paper, ethanol, Bunsen Burner, Yogurt, Pipette, Water, Spotting tile, Savlon

Concentration:
One control- Water
Savlon
One 100%
One 50%
One 10%

Hypothesis: 
I believe that the higher that the concentration of the Savlon the bigger the size of the clearzone will be because I think that the savlon will prevent the bacteria from spreading


Method:

1. Gather the equipment.
2. Using a marker pen on the jelly-side label the sections for the different dilutes
3. cover the jelly with yogurt
4. Dilute the Savlon to 100% 50% and 10%
5. Using hole punch punch out 12 pieces of filter paper (4 for each plate)
6. dip the paper in ethanol using sterile tweezers and run through the Bunsen-burner after each time. then dip the circles into the different concentrations and water and then put them into different sections of the plate.
7. tape up the agar plate and let the bacteria build up

Variables: 

Independent Variables: Savlon

Dependent Variable: Size of the Clearzone (mm)

Controlled Variable:  Size of Agar plates, Size of Filter Paper, Type of Disinfectant

Factor:

• Contamination of agar
• Agar Cracks
• Amount of yogurt used
• non sterile tweezers

Concentration (%)	Clearzone 1 (mm)	Clearzone 2 (mm)	Clearzone 3 (mm)	Average
0%	0	0	0	0
10%	13	18	20	17
50%	22	25	25	24
100%	28	29	35	30.66666667

Conclusion: After analysing our results I have concluded that when the concentration of the savlon is increased the size of the clearzone will also increase. Bacteria is asexual meaning it can reproduce by itself. Bacterial reproduction starts with a parent cell and the parent cell begins to replicate itself. Next the cell grows and begins to divide from the parent cell until they are split apart and there are two daughter cells, bacteria uses this form of reproduction so they can multiply quicker. Savlon has an active ingredient called chlorhexidine which is a disinfectant and an antiseptic. It is bacteriostatic meaning it will prevent the bacteria from spreading and it will interrupt the reproduction cycle which is why there is a clearzone around the savlon. Since the savlon creates a clearzone the bacteria can't form it's colony so it ends up dying.

Bacterial Structure:

• Flagellum
• Capsule 
• Cell wall
• Cell membrane
• Pilli
• Cytoplasm
• Ribosomes 
• Chromosome
• Plasmid
• Endospore

Evaluation: The results of the experiment are exactly as I expected the savlon prevented the bacteria from spreading just as I predicted. If I was to do this Experiment again I would use different concentrations so that I can see a bigger difference in the size of the clearzone.